4.1.3. Recursion Levels Definition

A company is assumed as a viable system that is the first level of recursion in which the five systems neededto ensure viability are found. Therefore, in this research work, four levels of recursion can be differentiated as it is shown in Figure 6:

	- - The recursion level of plant or production workshop, for example production management activities in an automotive production or assembly shop (n + 1),
	- - The level of machine group, machine or installation with the associated activities for the different production activities such as preparation of the machine, change of tools, operation, control of production, etc. (n + 2),
	- - The recursion level of plant or production workshop—for example, maintenance management activities in an automotive production or assembly shop (n + 1),
	- - The recursion level of installation or machine with the associated activities for the different maintenance activities: preventive, planned repairs, corrective, etc. (n + 2).

The activities in the recursion level n + 2 are no longer viable systems in contrast to the higher recursion levels because they do not contain a structure like that of the VSM, since they are the elements of production or maintenance execution.

Within this first level of recursion, company, the different functions of a company can be found, such as production, maintenance, commercial, finance, research and development, information systems, etc. In this research project, production and maintenance tasks will be analyzed in detail, recursion level n, but also considering the function of system 2 at the company level, n − 1, whose function is to coordinate the different functional areas of a company.

**Figure 6.** VSM recursion levels for company, production and maintenance (own elaboration).

System 2 at company level plays the role of coordinator between the functional areas of the company trying to solve conflicts between them. Moreover, systems 1 at company level are all functional areas of every company such as production or maintenance. At the recursion level of production and maintenance (n), it is assumed that the different production plants or workshops will be the respective system 1, which also contains a viable system in each of these locations. The VSM of production and maintenance management within a company is described in the next paragraphs by the tasks performed by its five necessary systems:


Figure 7 was developed as a result of applying the VSM for maintenance management. In the same way it was done for production management following the descriptions of the previous paragraphs:

**Figure 7.** VSM analogy with maintenance management (own elaboration).

4.1.4. Association of Planning Tasks to Recursion Levels

Production and maintenance management tasks were assigned to the VSM systems at recursion levels n and n + 1 defined before. In Table 1, the strategic production management tasks are classified and the tactical maintenance tasks and its classification to the VSM systems are shown in Table 2. It was done for all other production and maintenance tasks in the same way:




**Table 2.** Tactical maintenance management tasks and its classification to VSM systems (own elaboration).

4.1.5. Identification of Information Flows between Recursion Levels

Current technical literature agrees that the connection interfaces between recursion levels is extremely important [38] (p. 59). The goal is to determine basic links that can be transferred to any VSM in any company. The intensity of this connection between the levels varies according to the company [38] (p. 59). An exchange of information within the company and between levels of recursion is necessary to control the corporate environment, which generally has more information than can be processed in the company [14] (p. 287). Between the recursion levels, the following communication flows for both production and maintenance can be found:


Between the two normative systems of company and production/maintenance, there is a flow of information that defines the degree of freedom of decision-making in which production/maintenance recursion level can act. Specifically, it means that the decisions taken by the management of the company are communicated to production and maintenance management defining its guidelines for autonomous decision-making within the respective areas. These guidelines can be financial, on personnel, on affectation to other areas, etc. In the same way, the objective levels such as production in term, production quality and production costs and adaptation capacity are influenced by decisions from the management, defining the priorities and the limits for the coordination among production areas. An example could be: the direction of the company in its strategic plan establishes the target production volume for the following years as well as the required flexibility in percentage on the production as well as the decrease in target costs. Of course, these decisions would influence the decision-making framework for production and maintenance that should adapt their methods and tools to be able to optimize costs, times and quality based on that flexibility also securing the required availability and adapting its maintenance strategy.

As explained during the research work, basic communication flows were defined. In total, 88 information connections were defined for the production recursion level specifying if the communication goes from company's recursion level to production recursion level or between systems in production recursion level. Moreover, for the recursion level of maintenance, a total number of 77

information connections were defined specifying if the communication goes from company's recursion level to maintenance recursion level or between systems in production recursion level. An extract is shown in Table 3 for the communication flows of the production recursion level:

**Table 3.** Extract of information flows in the production recursion level (own elaboration).


#### *4.2. Applying the Conceptual Model to an OEM Production System*

The automotive supply chain is composed of suppliers at three levels (Tier 1–3), OEM (car manufacturers), distributors. For the work, we are going to focus on the production process of an OEM [39] (pp. 23–32):


Efficient logistics management is becoming a reality to survive in the automotive sector. The fragmentation and segmentation of vehicle models (such as hatchbacks, sedans, vans and pick-ups, cross-over coupes, roadsters, two-seater vehicles, SUVs, etc.) are growing. The complexity of customized models and variants is on the rise, especially as regards the way individual vehicles are equipped. The key trend in automotive production is the standardization of construction modules in common platforms. The modules refer to groups of components and related systems. The diversity of models is an important sales argument and delivery time is the key factor for the automotive market and in the manufacturing process. These requirements involve a change in assembly operations that need to be more flexible and agile [40] (pp. 24–25).

In the automotive industry, there are two approaches depending on when to start the assembly process. In the current market, most OEM producers use both to a greater or lesser extent:


On the other hand, and regarding the importance of maintenance in the automotive industry, it can be foreseen that, with the increase of automation and mechanization in the automotive industries, the production processes are becoming very sensitive to the machines and the human factor. Consequently, the role of equipment maintenance in the automotive industry as a mean to control and reduce costs while achieving the highest standards of reliability plays a fundamental role [41] (p. 514).

### *4.3. Model Simulation Using System Dynamics for an OEM Production System*

In this step, the conceptual model for a manufacturing process is specified. To do this, the interrelations between indicators are defined by Causal Loop Diagrams (CLD). Later, the concepts

are modeled in the VENSIM commercial simulation program. The simulation models present a simplified depiction of a real production and maintenance process to quantify the effect of decisions in a production system. Moreover, it contains the validation of the models and the presentation of the results obtained. Finally, the main conclusions are summarizedas well as a critical reflection of the work including a perspective for future research activities.
